Schedule III: Rollforward of Real Estate Assets and Accumulated Depreciation (Details) (USD $) In Thousands, unless otherwise specified	12 Months Ended
	Dec. 31, 2012	Dec. 31, 2011	Dec. 31, 2010
Reconciliation of carrying amount of real estate investments rollforward
Balance at the beginning of period	$ 906,907	$ 897,312	$ 879,833
Less: Fully depreciated assets	0	0	(63)
Balance at the end of the period	911,792	906,907	897,312
Reconciliation of Real Estate Accumulated Depreciation [Roll Forward]
Balance at the beginning of period	136,460	112,765	91,247
Real Estate Accumulated Depreciation, Depreciation Expense	24,366	23,695	21,581
Less: Fully depreciated assets	0	0	(63)
Balance at the end of the period	160,826	136,460	112,765
Land Improvements [Member]
Reconciliation of carrying amount of real estate investments rollforward
Real Estate, Improvements	0	0	0
Building Improvements [Member]
Reconciliation of carrying amount of real estate investments rollforward
Real Estate, Improvements	3,776	49,027	94,188
Construction in Progress [Member]
Reconciliation of carrying amount of real estate investments rollforward
Real Estate, Improvements	$ 1,109	$ (39,432)	$ (76,646)